Option 1 - Replace Fixtures
Loosen the two screws in the slots. Rotate the fixture so that the screws end up in the larger holes at the ends of the slots. Pull the fixture down. You should find wires from the fixture connected to either individual wires or a cable coming from the electric supply. There may be multiple cables/wire sets - supply, switch, feed to other fixtures. Take pictures before disconnecting anything. Generally speaking, there will be 3 connections (hot, neutral, ground) to remove/replace in order to replace the fixture.
Advantages: Individual fixture control, multi-color control (with some LEDs).
Option 2 - Replace Switches
Similar to above (easier, because you don't need to climb up to the ceiling), but at the switch instead of the fixture.
Advantages: 1 switch might control several fixtures, no need to figure out the right size for each fixture (both physically and amount of light), safer as switch can always manually override "smart" controls.