it depends, if there are aspects of the team that depend on weather then definitely dont change it (e.g. powering up moves, stopping opposing sand damage). this can be very subtle. if you look at typical rain stall, you dont /need/ politoed, but it does help the team quite a bit. ultimately its the raters choice as to what to do, but typically removing weather is not a good idea, unless the team is bad.
that being said, always try and make a team as efficient as possible!