Collectively, Office add-ins and web apps are called extensions. Extensions are customized pieces of code aiming to improve your experience and productivity.
There are more than one way that you could use to install extensions. You should always install extensions from trusted sources.
To review what extensions are in effect, please follow the instructions below.
For installed web apps, if you are using WEB-BASED ONLINE VERSION OF OUTLOOK,
(1) Click Profile
(2) Click My account.
(3) Click App Permissions. You will see installed web apps.
Click Details to understand the nature. If you don’t trust any of them, click Revoke to remove the permission.
For installed add-ins, if you are using WEB-BASED ONLINE VERSION OF OUTLOOK,
(1) Click Outlook in Office 365 App list.
(2) Click gear icon. Choose Manage add-ins in Settings menu.
(3) Click My add-ins. Review each add-in listed in Store add-ins, Admin-managed add-ins and Custom add-ins.
(4) Choose View details in pop-up menu.
(5) For any add-ins installed from Microsoft App Source. You will see a detailed introduction page.
If you don’t feel comfortable with any of them, click Remove to have them removed.
if you are using SOFTWARE VERSION OF OUTLOOK, access Manage Add-ins from File menu.
Once log into Office 365 portal, please follow above instructions to access App Permissions.