I'm still very new to Lightroom, and I was wondering, if I remove a photo from one of my libraries while in the develop section, can I re add it if I actually liked it once it was removed? How do I go about doing that?
You can. However, the question is, what is it you are really trying to do?
If you remove a photo from your catalog, you lose all the edits, and it is removed from all the "folders" and all the collections.
Optionally you can also delete the file from the hard drive (this cannot be undone).
The better option might be to use the star rating system.
During the import process, I give every picture a rating of 2.
I set the filter at the top of the Library to show only the 2 or higher images.
If I find an image I don't like, I drop its rating to 1, which causes it to be "hidden" from this view.