To put two and two together, by your definition:
Antiracism is the active process of identifying and eliminating ideas that suggest one racial group is inferior to or superior to another racial group in any way
If there are observable differences between racial groups (not a contested fact I think?) then you are racist or not depending on your values. For example, if you observe that there is difference in average height between two racial groups, and you consider being tall to be good, then you are racist because you must therefore see one group as superior in that respect. The anti-racist response, according to your definition, must therefore be to eliminate the idea that being tall is good.
For example, if you are a basketball scout, and you disproportionately recruit people from one race over another because they are on average taller, then you are racist. Anti-racist activists would aim to change your "systems, structures, policies, practices and attitudes" to ensure that the opportunity to become a professional basketball player is distributed equitably.
But no matter how you implement it, to achieve that goal implies that someone who would likely have been a better basketball player is going to have to be passed over in favor of someone else who was scouted in order to boost the number of people of their racial group in the pipeline. That is, someone was given (or not given) something because of their race, at least in part. Many reasonable people would consider that racially biased, or "racist" according to the way the word is used in common parlance.