cant uninstall mods

Hi,

I installed a few mods on my realms server. Recently I changed my computer and I want to uninstall one of those mods and put another one in its place, however I cant access neither mods or textures on that realm and therefore i am unable to uninstall them. I also cant put new mods because of the error. I would really appreciate your help

Thanks in advance,

Mateusz