Help! I'm trying to update a custom account field to editable, that is currently read-only. I've tried going to Accounts -> Fields -> Click Specific Field -> Set Field Level Security and I do not have the option to unselect Read-Only. 

I've also tried to update the System Administrator Profile to allow for Edit Access under the speicfic Account Field but again - it will not allow me to edit the "Edit Access". 

Please HELP!