Icemakers need to be cleaned about every 90 days, especially if it is a bin type unit that holds recirculated water in a tank which is then pumped over a grate to make ice. You didn't indicate what type of ice maker you have. Many manufacturer produce a cleaning produce for their ice makers. Here is a link to the Whirlpool/Kitchen Aid product:
It is made primarily for a bin type ice maker and does an adequate job if you use it on a routine basis (i.e., every 90 days).
If your commercial ice maker has removable parts, remove all parts that have direct contact with the ice. Wash these parts in hot, soapy water and use a brush to remove any dirt or mildew from the parts. Remove any ice or water storage bins and wash them in soapy water. Rinse each part thoroughly to remove all traces of soap. Use a 50/50 vinegar/water solution to break up any hard water (calcium) deposits on the parts. Sanitize your ice maker parts by soaking them in a solution made of 1 oz. of bleach and 1 gallon of warm, clean water. Allow the parts to soak for at least 30 seconds and leave them to air-dry.
Clean and sanitize ice makers that do not have removable parts by running two or three cycles and discarding the ice. Check you manufacturer's instructions for how to clean your ice maker. Some machines may not tolerate diluted bleach solutions, so check the sanitizing solution specified by your instruction manual through the machine. Always throw away the first batch of ice made after cleaning. Also change your water filter, if so equipped.