It would be hard to do Comey in, since he has a 10 year appointment as FBI Director starting in 2013. -Tom
Plenty he could do with Comey.
Have his AG appoint Special Prosecutor to look into Comey’s handling of this case, including any malfeasance or conflicts.
Reassign him to new office space in the sub-basement without WiFi or air conditioning.
Etc. etc.
If there is evidence of a crime or even a cover-up by Comey, he can spend the rest of that 10 years in the pokey, plus more.
If President Trump wants Comey gone, he'll be gone.
If Comey resists, there is plenty of evidence to impeach him. Congress would be more than happy to do so.