To perform an administrative task from within a standard users account, it is often quicker to elevate to an admin account via Terminal rather than logging out and in again.

To do this, you need to open Terminal (located in /Applications/Utilities or search for it after pressing CMD-SPACE)

for this example, my admin account is named localadmin, so replace localadmin with your admin user shortname

in Terminal, type the following

su localadmin

Then hit Enter and you will be prompted for the password of that account, once entered correctly you will be running as that user.

NOTE: You will not be able to ‘su’ to an admin account which doesn’t have a password set.