i had the same set. i love the sound quality but retuned mine due to how theyre designed. i found that if you remove them from their earcups that can put alot of extra stress on the joint there. instead try to grab the metal headband and take them off that way.
itll help remove the added stress to that joint if you grab the metal headband instead.
as for the the broken set… your best bet would be to try and disassemble them at that joint and use some epoxy to repair the damage joint ive had alot of luck with JB weld in the past but i’m sure there are other good options for plastic out there. be sure to thoroughly clean the area before using the epoxy
good luck!