Hello,

Because SimpleStart only allows 1 user, you cannot change the Master Admin.  What you would have to do is upgrade to Essentials, add the other user as a Company Admin.  Then once they accept invite and show as active, transfer the Master Admin role to them,  Once they accept the MA role, have them log in and remove the old user account and downgrade back down to SimpleStart.

If you have them right there with you, or on the phone this can all be done in a matter of minutes.