I was able to remove DMC from my computer and iPhone. However, the "floating" DMC button was not removed from my iPhone. I've tried Dell Support and they could not help me. Any suggestions?

I found the following directions (from Microsoft) on the Windows 10 Settings -> Apps -> Apps & Features page:

Uninstall or remove apps and programs in Windows 10

Using those search words in Google, I found the following directions (from Dell):

Windows 10: Various methods to uninstall problematic Programs and Apps 

Good luck!

Go into settings for mobile connect, turn off “Runs at Log In,” select option to Terminate it, then do the uninstall option