The most common way to do what you want is to use Xerox Standard Accounting.
1. Configure Xerox Standard Accounting and assign user codes to the users that you want to be able to print in color. Link: https://www.support.xerox.com/en-us/article/en/x_wc7556_en-O19843
2. Configure Xerox Standard Accounting for 'Color Tracking Only'.
Now only the people with a valid accounting code will be able to print in color. The other tenants that weren't assigned a code will only be able to print in black and white. I recommend changing the default admin password on both of those machines as well in case any of those tenants take the initiative to get their color printing back by reconfiguring settings. If the default admin password is still in use that's very easy to figure out.
One of our client has 2 WorkCentre printers 7835 and 7845. They are on a windows domain and their server is windows 2019. This client rents out office space and allows the renters to use their networking infrastructure and printers. Now they are complaining about the cost of consumables and want to restrict the renters to only B/W printing! We do not have any access or control over the renters machines.
What is the easiest way of accomplishing this?