I only use black ink. I bought HP OfficeJetPro 8710, and now I need to replace color cartridges

[Waste_expense]

I'm an elementary school teacher, have a home printer and a classroom printer, and am one of a committee to buy new school and classroom equipment when necessary. Money is something teachers always worry about! I only print using black ink to save cartridge replacement money. In the past I've had an HP that allowed me to remove color cartridges when they dry up, and just continue with black. I bought the HP OfficeJetPro 8710 with extra replacement black ink cartridges. Although I've never used the color cartridges, now the printer says it won't print black and white pages because the yellow cartridge is empty (I presume dried up) even though I have plenty of black ink left. It won't print if I remove the yellow cartridge, which an earlier HP printer allowed. I'm saddled with a finicky printer that stops printing if any of the 4 cartridges registers as empty, even if never used. 

Does anyone know how to work around this? Could I just add liquid to the color cartridges? To me, this is pure gouging to force users to pay, and pay, and pay for unnecessary materials. If no one can help us with this, the school has bought HP printers for the last time. Please help! I hate being help hostage by a printer, or spending money that my class urgently needs for student projects.

[Valsimot]

HP OfficeJetPro 8710 will stop printing if any of the colour inks is empty even if you print only black. There is no option to bypass that. You can eventually when an empty ink cartridge is replaced set on your computer under preferences to print black and white only, that will minimize the usage of colour inks, but they will still be used for printhead maintenance.

Removing any ink cartridge from the printer is not a good idea unless you are changing ink cartridge, leaving your printer without ink cartridge and shutting it down without ink cartridge can cause the printhead to fail.