You don't need to "unlearn", what you do need is to "learn" how to focus that perfectionism in the right direction, and when to turn it off. For instance, you better be LASER focused on the details of an event -- when it comes to the Emergency Preparedness of the event execution team. When a fire breaks out at a 1,000 person event - THAT is not when you "think" about how to get them ALL out of there - you plan, you practice, and you are ready.
But, lets take table clothes. You ordered the Pearl White gorgeous table clothes, they sent the so-so regular white... do you freak? You shouldn't. It isn't important.
Do SWEAT the details when it matters --> not sure if it matters?
- Will the customer cancel the event if the white isn't pearl? Nope.
- Will the customer sue you out of business if people die at their even because your team was running for the door? Yeap.
Event Planning is a great career with rewarding benefits of seeing what you did.. but don't roll in thinking it is all puppy dogs and kittens, there are some real challenges in pulling off any event with more than 2 people in it... which makes it that much more fun, engaging, and rewarding.