Classical Space Clearing Techniques
Probably the easiest is to light a candle [preferably a long-burning one], and offer that Light to Spirit so It may cleanse and release any negativity present.
[a simple statement would suffice - e.g. I offer this flame to Spirit, so all negativity, all obstacles, all struggles may be released from my Life and this home ... May only the Light of Spirit burn brightly within me, and in my Life.]
Frequently playing a CD of Sacred Chants [no matter the lineage] will cleanse and uplift the energies.
Just remember that it will work slowly, and requires many days to achieve this.
The best smudge-sticks combine both Sage and Juniper together ... the best incense to use is Frankincense, Myrrh, Copal, Dragon’s Blood, Camphor, Cedar, Lemon, Mint ...
... and don’t forget to de-clutter, physically dust and clean the space, and consider painting an accent wall [use warn or bright colors where appropriate]