How to remove access from an iPhone

Good evening,

I worked for a while with companies to post on their profiles.

At the moment the collaborations are finished and I would like  to remove the accesses of these pages from my personal phone.  How can I do without compromising their pages but to finally be able  to stop viewing their pages as well? They are not connected to my page,  I have already tried to click on "sign out" from their profile hoping  to return and they no longer see the accounts,  but they are still there.

Thanks to who helps me