Rear wheels are out of line on 1997 w-210.. Tires are wearing bad on inside,, How can I align them????

Take it to a reputable alignment shop or independent MB shop. Make sure the shop is competent in assessing wear in MB’s 5-link rear suspension. IIRC only rear toe is adjustable so camber type wear like you describe can’t really be fixed by adjustment. Consider the overall cost. It might be cheaper up front to fix only what’s severely worn now but it might cost you less in the long run to have the rear suspension refurbished in one go.

Does the car have suspension modifications like lowering or cut springs?

Sixto
98 E320s sedan an wagon
02 C320 wagon

No Sixto--- Tires are wearing on inside??

Most likely sagging rear springs, especially under acceleration. This causes excessive negative camber, explaining the wear on the inside of the tires........

Thanks Guys