Systemic racism obtains when a system(s) function (regardless of explicit rules) to favour certain racial groups over others. It doesn't require overt individual racists (though it may protect and even reward them) nor does it necessarily require any conscious acts of racism at all (and obversely you could have conscious acts of racism in a system where no systemic racism exists, only rather than being performative of the system, they would be antithetical to it). Systems are culturally contextual, they're embedded in cultures and how they function depends on their relationship to the culture they're in. So, often it's what the system allows rather than what the system demands that's important. E.g. if you've got a justice or policing system embedded in a culture that's only recently emerged from the acceptance of explicitly institutionalised racism, you need extremely strong safeguards to avoid the continuance of implicit racism in whatever ostensibly non-racist institutions are substituted. Not having those safeguards in place means the explicit racism of before doesn't just disappear but finds footholds in the new institutions and festers there looking for opportunities to express itself.
Systemic racism occurs in all areas of social life, policing, housing, education etc. And again, it's not primarily about explicitly racist acts or explicitly racist policies or legislation but how things work in practice to disadvantage communities of color. Here's an example relating to housing.
https://www.americanprogress.org/issues/race/reports/2019/08/07/472617/systemic-inequality-displacement-exclusion-segregation/
"For much of the 20th century households of color were systematically excluded from federal homeownership programs, and government officials largely stood by as predatory lenders stripped them of wealth and stability.
In the decades preceding the Fair Housing Act, government policies led many white Americans to believe that residents of color were a threat to local property values. For example, real estate professionals across the country who sought to maximize profits by leveraging this fear convinced white homeowners that Black families were moving in nearby and offered to buy their homes at a discount. These “blockbusters” would then sell the properties to Black families—who had limited access to FHA loans or GI Bill benefits—at marked-up prices and interest rates. Moreover, these homes were often purchased on contracts, rather than traditional mortgages, allowing real estate professionals to evict Black families if they missed even one payment and then repeat the process with other Black families.57 During this period, in Chicago alone, more than 8 in 10 Black homes were purchased on contract rather than a standard mortgage, resulting in cumulative losses of up to $4 billion. Blockbusting and contract buying were just two of several discriminatory wealth-stripping practices that lawmakers permitted in the U.S. housing system."
Most likely, as with you, objections to the existence of systemic racism turn on a misunderstanding of what it is. As if it's just the type of claim that police are racist or police departments have racist policies. That's really not it. It's usually far subtler than that and, for being so, all the more pernicious.
In any case, I don't want to go off on a tangent on this. In asking how systemic racism can be solved (particularly in policing), the OP presumes its existence. If you want to participate you'll need to do so on that presumption (or at least not derail the discussion by making it about something it's not, i.e. stay on topic, please).