Hi @N E
Please note your issue is related to Office online, and is not supported on Q&A forum at current time ~
To help you better, it's recommended to post a new thread on Microsoft Answers Community.
Thanks for your understandings.
Based on my tests and the searching online, I found the apps on left bar at office.com are unable to change.
We can only customize the app launcher by clicking the app launcher in the top left corner .
Here are 2 similar thread, "Are we able to customize apps on Office 365 sidebar?" and "Is there a way to customize the order and what apps show up on the sidebar?".
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