The phrase "letted rip" is generally used to indicate giving something freely or letting something go without restraint. There are several synonyms you can use for this phrase, depending on the context. For example, you could say "unleashed" or "set loose" if you're talking about something that has been held back or restrained and is now being allowed to run wild. Alternatively, you could use "released" or "freed" if you're talking about something that has been held captive or restricted in some way and is now being let go. Other synonyms for "letted rip" could include "unburdened," "unleashed," or "unbridled." Ultimately, the synonym you choose will depend on the context and the tone you're trying to convey.