MSMA will kill bahia grass, Dupont Cimeron will do the job also. These two maybe be hard to find unless you are close to a farm supply store. Image crabgrass killer will also control bahia grass. Lowes has it.
1. Complete physical removal of the plants along with its root, otherwise it will re-grow.
2. Don't allow it to go to seed because it can go to seed in only a few days, requiring constant mowing.
3. By using chemicals.