Hi Robin Theodore,
Greetings. Thank you for your further reply.
I understand your concern and I’ve carefully read your description, if my understanding is right, it seems you want to remove the Teams channel in the Quick access menu under Save As tab. For the situation you’ve encountered, I do understand the inconvenience caused and feel very sorry about it.
As far as I know and after my research, the Quick access list for Office apps is a new feature that being rolled out gradually for the users. For your reference: Getting started with Quick access - Microsoft Support.

I’ve also done a test and further research about the situation, I’m afraid and sorry to say there’s currently no build-in settings to remove the Teams channel in this list or completely remove this Quick access menu as many other users have the same feedback as well. Here is the related thread: In Excel, how do I remove the Quick Access pane in the File Save - Microsoft Community and my test result as reference for you:

Due to this situation, since this is a new feature that rolled out by Microsoft, I sincerely suggest you can try to report the situation and your feedback to the Microsoft Support Team. The support team has higher permission to remotely assist you and advanced resources for the new feature of Office apps. This is a more efficient way in handling this case for you.
If you are an admin, I recommend you get support by following steps from this link: Get support - Microsoft 365 admin | Microsoft Learn.
If you are not an admin, you can contact your admin to contact Microsoft support. You can look for the way to find your admin through this link: How do I find my Microsoft 365 admin? - Microsoft Support
Please accept my apologies for redirecting you to the related team support, as the moderators in this community have limited resources to verify the advanced information and to get the quick and better assistance, we requested for this.
Appreciate again for your patience and understanding.
Hope you having a nice day.
Sincerely,
Harry | Microsoft Community Moderator