Let's say we have two Pinterest accounts, Profile A and Profile B. Profile A has Board A. We want to move this board to Profile B. Here is a way that I follow.

1. Create a new board Board B in Profile B.
2. Send collaboration invite for Board B to Profile A.
3. Accept the collaboration invite from Profile A.
4. Move all pins from Board A in Profile A to Board B which is editable by both Profile B and A. If there are sections, each of those need to be created and moved separately.
5. Remove collaboration access to Board B from Profile A. Now Board B has pins from Board A and is in Profile B.
6. Delete Board A from Profile A.