Defunding won't mean that the police will not be paid, it means that they won't be given as much money for military grade weapons that they're trained to use on civilians or money to pay compensations and lawsuits they constantly go through when civilians are either murdered* when being arrested or caught in the crossfire. Police will remain as the point isn't to eliminate the police.
To add to that, what Black Lives Matter is pushing for is reform, better background checks so that less violent and terrible people who want to become police for power are hired, perhaps people who handle stress better and are less likely to snap, etc. We want police, we just don't want them to hurt anyone anymore. There are many terrible and unjust people in the system, so much so that the "good cops" who might handle situations better or recognize their subconscious implicit biases (as in towards any race/gender/religion) and not allow themselves to make decisions clouded in subjectives are barely a speck of sand on a whole beach.
BLM is a movement of compassion and is to help everyone while pushing our world forward into a less biased system. But unfortunately some people do not understand that just because it is called "black lives" does not mean "Black lives matter /only/" but simply that it means "Black Lives Matter, Too". Just as has happened historically, the counter-movement "ALM" is aimed to undermine us and move attention away from what BLM is intended to do and, ultimately, is pretty useless as most counter-movements tend to be given they have practically done nothing but undermine BLM since its creation (editing videos to make BLM look bad, starting riots undercover at protests, spreading text book definition propaganda etc).
I would recommend you look up videos made by leftists explaining what we actually want out of defunding police instead of hearing it from other, more questionable sources. Of course some leftists are going to be more radical, but the same thing could be said about right-leaning persons.
*And before anyone gets mad at my wording and insist that "some lives have to be lost in pursuit of 'liberty'", don't you think everyone should have the liberty to be handled professionally? To be able to be jailed, rehabilitated and remain alive? It's a tragedy to lose human life so frivolously and without a second thought as to what to do about problems presented in our day-to-day lives. That person who was killed could've been a relative you loved dearly or a friend, a romantic partner, even.