Why is the Boston area obsessed with removing lawn clippings? No, granular fertilizer cannot be removed by mowing it. You should always leave your clippings on your lawn. Lawn clippings are mostly nitrogen and water and should be left to make your lawn healthier. Don’t bag the clippings, don’t let your landscaper bag the clippings. Clippings don’t lead to thatch and are not thatch. If you have clumps of clippings in the lawn after mowing hit them with a rake or blower to disburse them.
Don’t take my word for it, follow this link to the UMASS fact sheet on good turf care.