I’m hoping this will be an easy answer! I have looked in other posts on door hinges but cannot find the answer. 
 

Question is, are the hinges in the attached picture meant to just screw out? I can turn them a bit but then they get stuck, and I am wanting to replace them with some new ones!

Edited November 8, 20241 yr by George

https://www.diydirect.com/screwless-hinges-male-female-2-pack?gad_source=1&gclid=Cj0KCQiAire5BhCNARIsAM53K1jjMuOzbCLLxxOSa9VtLPixDUqOUBK_D2S-Fh_-6yVoyNFL4-Te_IAaAhK_EALw_wcB

These appear to be your hinges.

If so they screw in and presumably out.

Looks like they are screwed into a piece of threaded tube that crudely welded to the frame. There is corosion around the tube base and it looks like moisture could get in there. So most likely the end of the thread at the base of the tube has rusted and expanded so that now it has to cut a thread through the rust as it unscrewed. I would give both ends a dose of wd40 and then slowly increase the amount unscrewed by turning till it stops then screwing back in a bit, then out a bit more, then in again etc until a thread is cut thruough the rusty bit.

They are Anuba hinges apparently available from your friendly Fleecbay supplier

Heat would be the ideal solution but with the vinyl so close it's not going to be an option, but something like PlusGas will eventually get there, another option if feasible would be a small tray with diesel in, then invert the hinges into it. Alternatively if they snap, drill out & rethread