From a CBT perspective, I'm trying to do this by choosing my behaviors as if I weren't a perfectionist. First I've identified some areas where I think my perfectionism is more harmful than helpful - eg. getting anxious about emails and rewriting them, or spending far too much time and anxiety making a decision about a big purchase. Then I think what an average person might do - eg. send emails to friends without rereading, spend one day researching purchase and then make the decision based on that information. Then I make myself do the same!

But I don't force myself to 'let it go' in the sense of trying to force myself not to feel anxious. I change my behaviors and let myself fully feel the fear that those changes cause. I journal about it, identify biases. I sometime review later, to see if my fear came true.

Does that sound like something that could work for you? I think it's also important to do the deeper work in therapy, to understand why I feel the need to control things, why I feel excessive fear, and to empathise with my younger self rather than judge myself. But once I've understood that and decided to change, it's mostly about breaking through the habits to try a new way.