Or, rather than deleting them all, go in game, and use /addbotx <BotName> to add Zombies to team x.
Replace x with these numbers for the team:
Alpha = 1
Bravo = 2
Charlie = 3
Delta = 4
Replace <botname> with the bots file name (minus .bot) to load them.
Example:
/addbot2 Zombie
Also, to add more bots, type two slashes (//) to repeat the command you just typed in. Saves time.