Ok so i still have the file folder with RelevantKnowledge on my comp?

i cannot delete 1 file in this folder... it is a .dll app called rlls.dll and i cannot delete it.... i have looked in the Add/Remove programs and have gotten rid of rlevantknowledge on it but the folder is still there and it had that 1 .dll app and i cant delete it says it is in use still i have also looked on the processes menue for anythingthat looks like it is apart of it... and nothing.... i just cannot delte that 1 file and its rlly startin to scare me..... what do i do?