Step 2 : In the Registry Editor window, click on the Edit menu , select Find . In the Find window that appears, enter the keyword IsPinned and click Find Next .
Step 3 : At this point, the Registry Editor will display a list of keys but you should pay attention to the Default key - this key has a Type column as REG_SZ and Data column in the form of text. If the Data column of this key does not contain the name of the service you are using, such as Dropbox, Box or OneDrive, don't worry, press F3 to continue searching until you find it.
Step 4 : Once found, right-click System.IsPinnedToNamespaceTree and select Modify . In the Edit DWORD (32-bit) Value window, you reset the Value data value to 0 and click OK to complete the setup.
From now on, do the same for each cloud storage service that you want them to disappear from File Explorer.
Good luck!