You cannot/shouldn't renounce your US citizenship for tax reasons. [0] Every piece of advice you read from anyone online will say the same thing: if you must give a reason for expatriation (and you don't have to), say anything but taxes.
You don't officially have to give a reason to renounce, but consular officials might ask you verbally for your reasons. You are not required to give one though. You have the option to include a written statement, but I'm not sure why you'd ever want to take it (unless you really want to give them additional reasons to deny you entry).
If they determined you did for taxes, it's a no-no:
Former U.S. citizens would be required to obtain a visa to travel to the United States or show that they are eligible for admission pursuant to the terms of the Visa Waiver Program. If unable to qualify for a visa, the person could be permanently barred from entering the United States.
If the Department of Homeland Security determines that the renunciation is motivated by tax avoidance purposes, the individual will be found inadmissible to the United States under Section 212(a)(10)(E) of the Immigration and Nationality Act (8 U.S.C. 1182(a)(10)(E)), as amended.
https://travel.state.gov/content/travel/en/legal-considerati...
You don't officially have to give a reason to renounce, but consular officials might ask you verbally for your reasons. You are not required to give one though. You have the option to include a written statement, but I'm not sure why you'd ever want to take it (unless you really want to give them additional reasons to deny you entry).
[0] https://en.wikipedia.org/wiki/Reed_Amendment_(immigration)