The problem: you start a typical KDE application like Kmail and it requires your kwallet master password.
You forgot it?! – No problem!
The solution is very easy: To reset your KWallet password, delete the kwalllet PW-database.
great help. it worked. thanks
Bangarang, zeldor! Thanks for posting this quick fix!!! BTW, for Mint 19 the path starts with .local, not .kde…
I would say quick and dirty;)