The board of park commissioners or the township trustees may sell to an annexing municipality, upon terms and conditions mutually agreed upon, the whole or any part of any public square, public park, or grounds devoted to public uses for park purposes owned by such board or trustees when any such square, park, or grounds devoted to public uses for park purposes is or has been annexed by such municipality. Such board or trustees may sell by bid or otherwise to any purchaser any of its park equipment used on such square, park, or grounds devoted to public uses for park purposes.