djemyjenab Ah, I'm glad to hear you have found a way!
I've quickly wrote a short knowledge base article which I will mention in the main post in any case this happens again to someone else: https://community.v17.dev/knowledgebase/45-i-locked-myself-out
JasperVriends wouldn't it be easier to remove the extension with composer?
luceos my shared hosting cannot use composer. Learn the hard way cpanel - local host > cpanel 
Thank You Sir, @JasperVriends luceos
luceos Thanks, good point. I added that to the option-list! 
JasperVriends another option for people without direct db access might be the extiverse helper, it has a command to disable and enable extensions..
S4H have you read the article linked in OP? https://community.v17.dev/knowledgebase/45-i-locked-myself-out
I read but it didn't work sign in still no
first i removed it manually from cpanel i think i made a mistake there.
I installed the extension, but when I click the login button the form does not come up.
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Did you try disabling the extension? php flarum extension:disable flarum-third-party-login-only
note to anyone needing it, seems to be incompatible with fof/direct-links https://discuss.flarum.org/d/34158 - both register the route /login which results in an error
