Well it wouldbe better if you could give some more details what operating system etc.
I'll do my best deleting a folder, right click and choose the delete option.
Multiple folders hold down the Ctrl button on the keyboard left click all the folders you want to delete, then use the delete button on the keyboard.
For the rest? I saw a reply from Jester II where he said some virus's replicate folders etc. So hopefully someone will come along and advise you on this.