Hi I am making a mould for a part (manually) and I used a surface plane to split the mould in the way I needed it to be split. now I cannot get rid of the surface body, so in my part I have 1 surface body and one solid body. any help?

I have attached the file but because I have deleted some of the other sections of the mould I am not sure if this file will be enough, please let me know if you need any more info or files