Yes. It is important for you as the owner of the items to be decluttered to be part of the decluttering process. I will do the physical work, but it is important for you to make decisions about the items that you wish to pass on or keep and where you want to store them.
If the project requires packing or unpacking before or after a move then it may not be necessary for you to be there. This will be discussed and agreed with you beforehand.
If we have fully decluttered a particular area and I am working on an area designated for organising, then I am able to work there without you but only if discussed and agreed with you beforehand.