Did the Americans have the ability to bomb railroad tracks in order to disable concentration camps during WW2?

No. A broken piece of train track could be repaired fairly quickly, and European rail systems had a lot of excess capacity and track length to compensate for a line down for repairs. The US tried a similar strategy in the lead up to D-Day called the Transportation Plan, which tried to degrade German resupply efforts by attacking rail hubs and crossovers at first. After multiple thousands of tons of bombs dropped, there was no appreciable drop in rail traffic, and only saw success when targeting was switched to trains. That in turn was only possible in France alone where short-range tactical aircraft could patrol the country and accurately target rail traffic. That means that for the majority of the war, the Allies simply didn't have the ability to attack the German rail system in any way, and that's not considering doctrine, which said that attacking rail in any manner was a waste of time.

This issue is in serious need of correction: I was at Auschwitz a few months ago and the guide was asked a similar question, and he gave a vague answer implying conspiracy.

Anybody who has studied the bombing campaign, as opposed to just the Holocaust, could be in no doubt as to the near-impossibility of meaningfully impacting the death camps by such a means. Even had track destruction had a chance of success, ordering and carrying out such raids would have been militarily incompetent.

Behind such claims is the seeming assumption that an Allied air commander could just point at a place on a map anywhere in Europe and have it wiped out within hours. In fact bombing was extremely dangerous, finding even a particular city was challenging, and while hitting a target was hard, stopping it from being immediately repaired and actually affecting output was even harder again. And this went for a place like, say, the Ruhr Valley where the majority of German targets were situated. Most concentration camps were established further east- in large part to make them hard to bomb. Berlin was considered a very hard target by bomber crews and most concentration camps were hundreds of miles further into Germany.

So, Allied planners could try to wipe out, say, Germany's most densely situated industrial areas in Essen, a distance of about 300 miles from Allied airfields [in fact this was a common target, with casualties of around 5-10% of the force typical]. This would put out of action factories producing anything from gun barrels to radios to optical sights. Your honours English instructor and our guide at Auschwitz however think it nothing to send bombers to Auschwitz, a distance of 900 miles of heavily-defended airspace. Rather than being exposed to enemy fighters for around 400 miles, bomber crews would face them for 1600 miles.

And having flown that far, across relatively featureless terrain, the crews are then expected to bomb a railway track.

Now, by 1944 the Allies had studied their bombing and they knew a fair bit about it, and one thing they realised was that to put a target- especially a transportation target- out of action required repeated bombings. Only this way could they turn an inconvenience into a serious blockage. By mid-1943 targets were often being hit three times in as many days (once noticed, this made defence easier). From late 1943 the Royal Air Force tried to win the war by repeatedly bombing Berlin: the result was heavy losses and a defeat for Bomber Command's chief, Arthur Harris.

Next, consider a broken railways track in Poland or East Germany. Are the SS- who were essentially traffiking their victims to achieve industrial output while carrying out instant mass murder of those deemed unsuitable for work- going to shrug and give up on genocide? By what possible logic does some broken railway halt all this? Especially a railway many hundreds of miles away from any battlefront? The RAF couldn't stop Germany using the full rail resources of Belgium and Normandy, just across the English Channel. Rail centres like Cologne and Hamm, again the parts of Germany closest to England, were bombed incessantly yet they remained pivotal to Germany's distribution network.

So you have:

The difficulty of the mission
The need to abandon the bomber's other vital work against oil, munitions production, U-boats, V-weapons, canals and railways of economic use, dams, and the industrial cities themselves.
The presumption that such bombing could have affected the genocide.
The assumption that the Allies could have obtained the intelligence needed to support such operations.

For all the times I've heard this claim glibly put, I've never seen it presented in the face of counter-arguments by those familiar with bomber operations and the incredible challenges involved.