Why did Trump Repeal ObamaCare?

Despite efforts to dismantle ObamaCare, and despite changes to the law, Trump didn't actually repeal or repeal and replace ObamaCare.

There was initially a push to repeal after Trump took office, but that changed into a mostly unsuccessful repeal and replace effort.

The repeal and replace effort started as a plan put forth in Congress by Republicans and backed by Trump. Once that failed, the Trump administration set about repealing and replacing specific elements of the law using the judicial and executive branches.

That effort actually resulted in some changes like changes to the elimination of the the fee for not having coverage and the expansion of short term health plans. These changes that did actually pass are sometimes known as "TrumpCare."

You can see a list of changes under Trump here, but generally speaking Obamacare is still "the law of the land" and that means things like cost assistance and pre-existing protections are in place as of 2020. With that in mind, there is politically charged Supreme Court case that could end the ACA in the works, so that is worth noting.