There's a continuum of what "defund" means, but the idealists are pushing for actual, no-hyperbole defunding and disbanding. Police cannot be made good. They believe would be easier to reduce crime some other way than authorized state violence, and the funds could be redirected to those ways.
[0] https://www.wbur.org/hereandnow/2020/06/03/black-lives-matte...