Hi kaktusekgo,
Thanks for reaching out.
Unfortunately, once an EA Account has been linked to an FC Mobile account, it can’t be unlinked and then connected to a different FC Mobile account.
You can find more information here:
How to save your progress in EA SPORTS FC Mobile
The EA Account link is used to save and restore the progress of the FC Mobile profile it was originally connected to. It can’t be moved to another game profile, and progress or purchases can’t be transferred between the two FC Mobile accounts.
Before purchasing any add-ons, please make sure you’re signed in to the FC Mobile account where you actually want the content, as purchases generally remain with the account on which they were made.
I’m sorry there isn’t a way to switch the EA Account link in this situation, but I hope this helps clarify the available options.