There is no selective herbicide that will kill Bermudagrass or centipede grass that will not also kill other turfgrasses. The only way to get rid of them is to kill them with a nonselective herbicide such as glyphosate (Roundup) which will also kill other plants it comes into contact with. If the undesirable grasses are confined to patches, you may be able to kill out the patches and reseed or resod those spots. If they are scattered throughout the lawn, you may need to kill the entire lawn and start over. Bermudagrass is especially tough to get rid of. It often needs to be treated a couple of times, because it sometimes resprouts after one herbicide treatment.