As you are an Account Owner, you have permission to make changes such as removing or adding a user within your account.
How to remove a user
Log into your PageTiger account
Select 'My Account > Users'
Select 'Edit' for a user
Select 'Delete' to remove their access
How to add a new user
Select 'Add' to add a new user
Enter the new user's email address and name
You can also choose the 'Account Type' which defines the level of access the new user will have - find more information on different types of user here
Lastly, select to save your changes
You must be the Account Owner to make these changes within your account. Additionally, you can only make these types of changes within your own account and/or any child accounts sitting beneath your parent account. Find more information surrounding account terminology here.