Is it possible to safely clean the database from spam records?

Question

PostgreSQL

Hello everyone
There is a site with about 200k spammer accounts, and another 100k real ones. I was given the task to remove all the beaten guys from the database.
Is it possible to streamline the database by stupidly deleting all broken accounts? I read somewhere that it is generally undesirable to delete anything, since an index with holes can affect the performance of the database.