Hello, I'm trying to replace the power cord of an air fryer and there are these white caps that connect each leads. I would like to know if they can be removed without being destroyed, I quickly tried with flat pliers but it did no budge.

Aren't those twist nuts? You unscrew it and the wires seperate?

Never mind that looks like it has been crimped.

those look like crimp-on wire connectors. You'll have to cut the wires and get new ones or solder the wires together and heat shrink the connection.

I would not recommend a twist on wire nut in something that could be conceivably drenched, washed, or jostled enough that it could be knocked loose, nor would I recommend twisting them together and wrapping them with electrical tape in something that can get warm enough to possibly melt the glue.

Not sure of the actual name, but they're like wire nuts but crimped instead of twist. I don't think there's a non-destructive way to undo them but you may be able to rip the wires out and use a regular wire nut to splice them back. If not, try cutting them as far inside as you can and replacing with another crimp connector or use a screw type wire nut.

I've had some success taking pliers and gently squeezing the top and bottom of the crimp to open it, releasing the wires.

Some good points in the comments but the short answer is:
No, that is a crimp on wire nut. You cannot remove it without destroying it. If you remove this crimp on connector do not try to reuse it as it will never be as reliable again.

in something that can get warm enough to possibly melt the glue.

The yellow/green color scheme almost always indicates a grounding wire. (And the ground symbol molded into the plastic behind it seems to confirm that.) Unless something has already gone terribly wrong, there shouldn't be much power at all flowing through this wire, so it shouldn't get hot.

Well, it's an air fryer and there are other cables near it that look to be wrapped in heat resistant sleeves, so I'd err on the side of caution.

Cut, strip, and reconnect with a Wago 221

Gently squeeze the crimp, perpendicular to the previous crimp. That should allow a release of the wires. Would only reuse connector in a pinch. Badabam.