Unlike signing out of an online service, when you sign out of your Office program you are removing your account from your Office installation. When this happens, Office loses track of any customizations you might have made in the program. Also, the files you stored on a server will no longer be synchronized with your device.
To completely sign out of an account, you'll have to close all the Office programs you're running when you responded Yes to removing your account.
If you're signed in with more than one account, you'll have to sign out of each one.
You can sign in again with an account you signed out of. Go to File > Office Account > Switch Account. However, Office will treat it as a new account, meaning you'll have to set customizations all over again.