There are a few different ways to de-ess vocals. One common practice is using a spectral editor like iZotope RX to identify and attenuate the sibilance using a multiband EQ manually. This can be time-consuming, but it can be very effective. Another option is to use an automated de-essing plugin, like Waves SIBilance. These de-essers analyze the audio signal and dynamically attenuate the sibilant frequencies. This can be very effective, but it can sometimes result in artifacts if the plugin is overly aggressive. The third option is to use a noise gate with high thresholds and short release times to effectively mute the sibilant sounds while allowing the rest of the vocal recording to come.