You can unsuspend cPanel accounts from WHM. Follow this tutorial to unsuspend your cPanel user.
1. Login to your WHM Account.
2. Go to Account Functions >> Manage Account Suspension or type Manage Account in the search box and then the option will appear.
3. Under Select by Domain, choose the user you wish to unsuspend or if you know only the username, select the user under Select by User from the dropdown list. If the user is displayed in red color, it means he is suspended but if it is showing normally then the user is already unsuspended and you do not need to unsuspend it.
4. Click on the Unsuspend button.
The account will be unsuspended or if there appears any issue, an error message will display.