When you are reviewing the available talent for a project, if you see someone you want to remove from the talent pool option for that opportunity, you can "archive" their profile. To do this, click on the small "x" in the upper left corner of their talent tile.

This will remove that person from the role results for that project.

This isn't necessarily permanent - if you want to re-add them into the talent option pool, you can click on the "Archived" button on the left side of the page above that section of role matches on the project page.

And that will show you the talent you have archived for this project.

To re-add them to the talent pool options, just click the small "plus" sign in the upper left corner.