"To remove any clumps" means to get rid of any lumps or clusters that are formed together, usually by separating the individual parts so they become separate or smooth. Full definition
Mix well to fully incorporate all of the ingredients and to remove any clumps of matcha green tea. (soapdelinews.com)
It wasn't too much of a problem, I just had to make sure to remove the clumps from the surface and not to let them dry into the paint. (sawnailandpaint.com)
Make it a habit to clean the litter box by removing the clumps daily and changing the litter once every few days. (petsmagazine.com.sg)