One of the characters in my game currently has the Stupefied 1 condition from a Yellow Musk Creeper. I cannot see how this is removed.
I can't see anything in wounded
As an add on. If they contract a disease that gives Stupefied 1 as it's first stage does this overlap or stack? I would have thought overlap...
There is no duration so it looks to be permanent until removed. As for how to remove, I would use the same removal procedure as listed in the sidebar for "Recovery from Thralldom".
A creature that’s transformed into a yellow musk thrall or brute doesn’t die right away, although it no longer retains its personality, memories, or abilities as long as it exists as a thrall. Within the first few days after its transformation, a thrall or brute can be restored to its normal life with any magical effect that can remove disease or a 1-hour procedure that requires a successful DC 22 Medicine(expert) check and deals 2d6 slashing damage to the thrall or brute.
You need to get rid of those parasitic tendrils after all.
As for the Stupefied 1, any other source would overlap, not stack. The highest value takes hold for as long as it exists. (They were very specific in the creature description that multiple stupefies done with Bore Into Brain stack for the Creeper but that is an exception.)
See p 623 CRB "Redundant Conditions".