The only thing you can get rid of is snails and even they are hard to kill 100%. Just dip the plants in a week bleach solution of 1 part bleach to 19 parts water. Then add the plants for 1-3 minutes. The more delicate the plant the less time is can cope with, like hornwort and other fine leaved plants. Bigger, tougher plants like swords and anubias species can cope with a bit longer (up 3 three mins). But all that said, it wont kill other bacteria that may be actually inside the plant and if you're not careful you can kill all the plants you have, which is just plain silly!
If you got the plants from a reputable dealer, them they should be fine, I sometimes give mine a rinse under the tap but that's about it.
Sam