There is an excellent site for planning transferring to the UC and CSU systems. The deadlines for Fall 2019 are mostly past for both UC and CSU for transfers, however.

www.assist.org Shows transferable coursework from CA CC students to the CSU or UC campuses. Also shows recommended and/or required coursework for transferring to specific majors.

For transfering to private schools or out-of-state (non-CA) public schools, there is not a similar go-to recommendation for sites, so the best place to look is always the college's transfer admissions website.

Transfer students sometimes need to submit test scores, sometimes not. The UC and CSUs do not consider test scores for transfer admission.

Dewey

As a former Admissions Director, I can say the request for the submission of a graded paper has less to do with the grade itself and more to do with the validation of an authentic work by the student.  It would confirm a genuine sample of written work.  As a result, the need to discuss the grading between admissions and the teacher is irrelevant and unnecessary. 

Mark Cruver

I would almost never cancel an AP score, and here's why.

AP scores are literally NEVER required for college admission.  Students who excel on their AP exams can send them, but admission offices won't wonder where they are if they are not part of a student's application, and students will not be penalized for not sending or reporting AP scores.

AP scores ARE used to earn college credit after you enroll at the college you choose in the end.  Most colleges will award some credit for scores of 4 or 5; some colleges will award some credit for scores of 3.  No colleges reward credit for scores of 1 or 2, but there is no downside to having these scores show up on the AP report when you send your AP scores to the college at which you enroll.

If you cancel an AP score, you will never know what score you receive!  So I really can't think of a situation in which I would cancel an AP score.