Manitoba PNP should not think that you lied when you applied for PR and that you never intended to settle there. In order for them not to think that, you should spend at least 6 months in Manitoba after you landed as a PR. If you have already spent 6 months in Manitoba as a PR, then you are free to go. There are no cases as far as I know of a PNP going after PRs for leaving but in case they do in the future, you should at least stay your 6 months so you can say that your intention was to settle in Manitoba when you landed.