Exactly what the title says. I would love to know if you can fully delete or lower the permissions of an admin account that is currently in use (from aforementioned account). Thank you in advance!
You can lower the privileges of the current user using the parental controls.
You can find the details here
In one of the tabs you can activate this for the current account,
No - admin users or not, you can't delete the logged in user using the system preferences panel.
You can remove admin permissions, but until all processes get killed (logging out will also work), the running processes are still privileged.