Log into Office 365 with an administrator account
Navigate to ADMIN>SharePoint Admin Center
Click Manage Licenses
Click on the app you want to remove
Click on the dropdown ACTON’s item and select Remove this license
Navigate back to the Apps Menu
Click App Permissions
Click on the black cross (x) next to the app you wish to remove
Your app is now removed.
Next to look at how to remove SharePoint apps using Powershell.