I totally understand, mate!
😀
Well, in this case, you can use some third-party partition tools to help you perform the conversion at your own risk.
Unfortunately, I cannot recommend anything specific as I'm an official rep, but I'd suggest you
take a look at this thread from the community. I hope you find your answer there.
I'd still backup important files somewher else as well, though. Better safe than sorry, right?
Good luck!
SuperSoph_WD