Disconnect Fortnite / Psn account?

Back then I made a Psn / Fortnite account for my girlfriend, she installed fortnite on my cell phone a few months later, connected the two accounts, now there's the problem that I no longer have the password from the Psn account, even him I wanted to ask whether you can disconnect or delete the connected Psn account from the cell phone without deleting the cell phone account?

Urgently need help.

I don't think so since they are connected you would normally lose the cell phone acc I think;)

Play Fortnite myself but only have 1 ACC on the Ps4 and on the mobile phone, so unfortunately I don't know either

Then I thank you