You can't argue self-doubt into leaving. It isn't a position that responds to evidence — people with cabinets full of proof still wake at five convinced they have fooled everyone.
Release works better as setting down than as winning. Shopping bags at the front door: you don't defeat them, you just stop carrying them for a moment and notice how much your hands were aching.
The doubt may well be back this afternoon. That's allowed. Putting it down for the length of one task — the meeting, the call, an hour of actual work — is the whole practice, and it repeats.