Transfers can be used to bring more people onto your roster, or remove them from your roster at any point.
As per the Respawn League Competitive Ruleset, all transfers must be completed prior to Roster Lock. Roster Lock will now come into effect at the end of Week 6 for each season and format. What does this mean? Essentially you will not be able to add anymore players after this point. If you want more information, check out our Roster Lock post in the League Information section of our Forums.