Once you click on the Maintenance menu item under System menu item in your nopCommerce admin menu, It will display the nopCommerce maintenance page as shown in the image below with the Delete expired tokens maintenance item as displayed in the image below.

The above maintenance box allows administrator to delete the records about all expired and used refresh tokens from the table to free-up space.

If Include revoked option is checked while deleting expired tokens then it will also delete the records for which the access token was revoked manually from the Active tokens page.