Lincoln’s suspension of habeas corpus was unconstitutional (Ex Parte Milligan 1866). A US president could declare the 2nd Amendment (or any other) suspended, but good luck enforcing that. Particularly the 2nd.
The Second Amendment doesn’t give you the right to do anything. It PROTECTS the right that already exists from government interference. Suspend it, abolish it, do whatever you want to it. The nature of the Second Amendment is the intrinsic right of every human being to self defense. No law made by man can suspend that.
And good luck trying to find all those guns esp. those that accidentally wound up on the bottom of some lake or ocean floor as they were being brought in to be surrendered.