Peace be upon you. It is permissible to dispose of property that is subject to khums, but the khums must be paid immediately. (Source: Special Inquiry)
According to Sayyid Khamenei: It is permissible, but khums must be paid immediately.
According to Sayyid Sistani: It is not permissible to dispose of property after the year has ended without paying khums, and it is also not permissible to dispose of part of it even if the amount of khums remains in the rest. (Source: Minhaj al-Salihin, Vol. 1, Issue 1256)