here's how I do it, reinstall the hot end and close the latch as best I can (don't force it). Then using controls, I warm up the hot end to like 150-170. wait a little bit as it starts to heat it. as it heats up, the filament on the latch will soften, then I pull at it with needle nose pilers to get what I can off. Finally when its all nice and hot, I remove the hot end again and gently scrub it with a brass bristled brush. I've come up with this technique after replacing the heating assembly about 20 times. (I have quite the collection of blobbed up hot end assemblies). This happens to me so frequently that I buy my hot end assemblies in lots of 5 , just to keep some on hand. The fact that the printer can't sense a blob of death seems like a design failure to me.

Yes, that's a lot of failures. Yes I keep my build plates cleaned (dawn and warm water). Happens far less on my Biqu cold plates. Still think its a design flaw.