I just found a way to remove a tile from the "Recent Applications" home screen in IDMA.
There is a way to open the old workspace page (though not officially supported and not working as expected):
- create an action button in a view or form of an app that you can open in IDMA
- as action formula use @Command([WindowWorkspace])
When you click this action it will bring up the old workspace (in Notes 10 design). From here you have context menus on the tiles (you cannot open the apps from here with a double tap). Choose "Remove From Workspace" and the tile is also gone on the home screen 
There are also other options to open a replica from a different location. If you try to open the ACL though it will result in an error message "insufficient memory".
Found in: https://ibm.ent.box.com/v/DMA-EN
Please vote!
I also posted an idea of having the workspace page instead of the "Recent Apps" page as the default home screen in the idea channel: https://domino.ideas.aha.io/ideas/DMA-I-5