Your question is not clear. Either you are asking whether it is normal practice to remove systems, or you are asking whether it is normal practice to have CO2 systems within a MCC "system".
Normal practice is to maintain fire suppression systems, not remove them.
If you are asking whether it is normal practice to have a CO2 system within a MCC, more informaton is required.
I thought of the following questions right off, there are probably a lot more:
1. Why do you want to remove the suppression system?
2. Has something changed to make the CO2 system unsafe? (Is the space now occupied, or normally unoccupied, as opposed to unoccupied.)
3. Is it spot or total flood system? Is it a high pressure CO2 or low pressure CO2 system?
4. Is the system protecting the area within an enclosure for just the equipment or is it within a larger room that houses the equipment?
5. What kind of equipment is being protected?
6. How old is this system?
If it is an older installation there may be a better way to protect the area and resolve other concerns.
Normal practice may have changed, but I doubt that going from something to nothing is a good idea.