How do i print in grayscale on L335

If by grayscale, you are wanting the printer to output using only K ink, this is a RIP function. In the SAI Flexi RIP that ships with the Latex 335 printer, it is located in the Job Properties dialog, under the Color Management Tab > Color Correction - set the list box to No Color Correction.

This action causes the color data to pass directly to the printer without adjustment. This generally works best for CMYK-based files. Other RIPs have parallel functionality. Note that you may note a slightly grainer looking image, due to the sole use of K ink in gray tones. See attached screen grab from SAI.

Hello,

It is correct, however there are some additional settings to be made: please select Color mode GreySackle (8bits).