Changing the master admin in QuickBooks Online (QBO) is easy peasy, @m-azam.
When you want to change the master admin, you'll need to make sure you're logged in to QBO as the current master admin. Then, choose the existing employee you want to be the master admin.
Here's how:
Click the Gear icon, then select Manage Users.
Find the existing employee you want to be the master admin and make sure he/she is listed as Admin. If not, select Edit to change them to an admin.
Select the down arrow beside Edit, then select Make master admin.
Choose Make master admin to confirm the changes.
Then, ask the newly appointed employee to accept the invitation.
However, if the person who has the master admin account is no longer available, send us a request to change the master admin.