how to save CMYK images photoshop 2020

we use lots of printers and they all need the images to be smyk

By @mortal5F86

You always need to know which CMYK profile to use! There is no such thing as a generic "CMYK". Each CMYK profile corresponds to a specific print process, an offset press calibrated to a certain standard, using certain inks on a certain paper stock. The printer should always tell you which profile to use. You need to check this with all your printers.

Don't use Image > Mode. That will just convert to whatever you have set as working CMYK. The Photoshop default  is US Web Coated (SWOP) v2, just because there has to be some default, but that may well be the wrong one. If you're outside North or South America, it will certainly be wrong because it's not used anywhere else. 

It might be better to keep your master files RGB, and convert to CMYK on delivery, as required.

we have lots of files each day and if we want to save them as tiff the drives will get full soon.

File format has nothing to do with RGB or CMYK, as long as the format actually supports CMYK. If it's supported in the file format, Photoshop can save to it.

Hi. Yes, of course, you can. Image > Mode > CMYK and save it in a format that supports CMYK mode like TIFF, PSD, etc.