Related to this question:
If you change your mind having to do with this most important summit, please do not hesitate to call me or write.
I'm tempted to simply close the question as off-topic because the sentence is simply poorly written and is a poor example for English learners. Ordinarily we close these kind of questions, where we can show the text contains some kind of error.
However, since it's written by Donald Trump, currently the most influential figure in American politics, it seems a disservice to English learners who are likely to scratch their heads over his tweets and letters and other linguistic abuses.
Moreover, I wouldn't want this to be seen as a political decision, based on personal opinions and not the value to the community.