Hi,
Thank you for posting in Microsoft Community.
I understand that you are trying to disable the Add Profile option in Edge Settings. As this is a built in feature, there could be limitations on customization of these features.
However, you may want to check the Group Policy Settings or Registry Settings for the same. If you are using Windows 10 Pro, then you may access the Group Policy Editor by typing gpedit.msc in the search on Taskbar. If you are using Windows 10 Home, then you may have to check the registry value by opening Registry Editor by typing for regedit in Search.
Note: Before proceeding, make sure to create a System Restore point on the computer
You may refer BrowserAddProfileEnabled document for policies for Microsoft Edge.
Registry disclaimer: Important this section, method, or task contains steps that tell you how to modify the registry. However, serious problems might occur if you modify the registry incorrectly. Therefore, make sure that you follow these steps carefully. For added protection, back up the registry before you modify it. Then, you can restore the registry if a problem occurs.
Please take a backup of the registry. Follow the steps given in the link below:
How to back up and restore the registry in Windows
I would also you to post your query in Microsoft Tech Community for Edge, where you should be able to get in touch with the professionals with expertise on this query.
If you have any feedback or suggestions based on your experience using Edge, you can certainly help us improve the features by sharing your feedback. You can
Open Microsoft Edge. Click on the Settings & More Ellipsis (…) on the right hand corner and then, select Help & Feedback and select Send Feedback