Control Access to the Org: Create a guest administrator user and deactivate it- I am not able to deactive one of my Admin( the highlighted one) account to commplete the hands-on challenge.

I chose the "edit" option to deselect the active choice, but the checkbox remains unresponsive, preventing me from unchecking it. Could deleting this account be a viable solution to fulfill my challenge?

Here is the challenges directions: 

Create a new user: 

• Profile: System Administrator
• User License: Salesforce
• Username: must contain guestadmin somewhere in it
• Alias: guestadm
• The new user must be inactive