You cannot convert a Non payroll user into a Payroll user. You will need to set them up as a New starter in ESS and send them to payroll, or set up a new record in MicrOpay Evo and Sync back to ESS.
If you want to use the same sign in name for their new record, you can edit the sign in name of the Non payroll user and change it to something else. You may also choose to disable this account so that it can no longer be accessed.
To edit the Sign in name:
Go to the user profile in ESS.
Select Account Settings.
Click the Edit Icon to change the Sign In Details.
Enter a new Username.
Click Save.