You can remove projects from an existing album
A project can be part of many albums
Steps
Access the Album you want to remove projects from
You arrive on the Album
Click the More Options button in the album cover
Select Projects from the dropdown menu
You arrive on the Curate Album page: projects already in your album are listed on the right side
Projects already in your album will have their checkbox already ticked.
In this left side section: Untick the checkbox next to each project you want to remove from your album
Press the Save button
You return to the Album