If you host cell is adherent, that's easy, just wash (gently) with 1xPBS. Depending on the volume, standard practice is 3. You won't get rid of everything, but you should be able to clear most of the nonadherent bacteria.

If the host cells isn't adherent... that would be difficult.

Shen-An Hwang is right. The norm is to wash your adherent cells several times with PBS. Although this helps, we tend see a lot of extracellular bacteria still hanging around. We usually add an antibiotic (eg.gentamicin) to the media post-wash to kill off any remaining extracellular bacteria.

Dear it is required that you have several washing with PBS and finally with antibiotics.

Shen-An Hwang my cells are suspended !!