If you try to "clear your house" from possible spirit tenants, they will probably be agitated. They have lived there before you, so it is impolite to try to kick them out. Of course if you are a great yogi, you might be successful, but probably you are just asking for trouble. Therefore it is better to do nothing. In that way you "do not disturb anything already staying there unseen" as you said.
What you can do however, is to "bless the house" and all who live there, including any possible spirits. Having a good motivation and a little respect towards them is proper decorum. (For instance in Thailand, all buddhist houses have two altars made for the spirits of the ground and the regional guardians. As they are given respect and occasional gifts, they will be pleased and cause no harm.) You can chant the
Metta Dharani either in Pali or in English, for instance, first when you move in, and regularly afterwards. The mind of love protects you, and make the possible spirits realize that you are not a threat, but a friendly one, and they will do you no harm. Or, if you do a Buddhist puja when moving in, and make offerings not only to the Three Jewels, but also to the spirits, they will be pleased. Many tsog-pujas have already a special section for making offerings to the spirits - like the guru-yoga of Tsongkhapa, called Lama Chöpa. Or the guru-yoga of Tsongkhapa with requests to Dorje Shugden, called Wishfulfilling Jewel.