In NBA 2K20 you can change and respec your My Player builds. When building a player you will be able to select your Takeover ability in your My Player builder file. You can also go back and do this at any time in your My Player build file by heading to MyCareer and then selecting your build and then editing it.
The important thing to note here is that just because you head into the MyPlayer Builder File and change the Takeover in your build, you will actually need to create a new player to use the new build as your MyCareer player and the MyPlayer builder file are two separate things and any of the VC or upgrades that you’ve made to a MyCareer player will not carry over to a new character.
So if you like everything about your MyCareer player, except for the Takeover it does appear that you are out of luck when it comes to switching it mid-career. However, if you are only a short way into MyCareer and you don’t like the Takeover for your current build, you can change the Takeover in the MyPlayer Builder Files, but you will need to start over from square one with this new player.
Unfortunately, there is no alternative method to changing the Takeover for an existing player. Badges for your Takeover can be edited, however.