Can someone tell me how to delete WP Smush it

WP smush pro and WP smush it are NOT working on my install, probably due to a caching plugin. But I want to remove both of them and compress my own images.

However, when I look under the plugin section, there is NO DELETE button for getting rid of the files??? I network deactivated both, but would like to get rid of each?

I guess I could use FTP, but why is there no DELETE option on these plugins?

Thanks.