I have my pictures in 2 catalogs. One is for work and the other is my catalog (personal) My work has only work pictures but my catalog has personal and work. Can I remove the work photos in my catalog?
I suppose you can select your work file by a common keyword or similar criteria.
The principle is that you select all those files and hit the 'del' key or choose delete from the file menu. You choose the option NOT to delete from disk, obviously. Then you wait... a long time for the process to finish. The process will even probably abort if you have to delete many thousands of files at the same time. That depends on your available RAM. So, do a few tries to find the right batch size depending on your hardware (about one thousand for me).
A simple and fast solution to be safe for the process is to make a simple copy of the catalog folder from the Explorer or Finder. The catalog location is given by the menu File >> System Information.
If you want to mask the work files immediately before you have time to delete, I suggest you simply use the 'hide' feature for the selected files.