Basically install stylish on your browser of choice as an add-on and install this stylish theme to remove all images from signatures.
How to:
Install Stylish
Find Manage Themes button
Press Write New Style
On a blank page just copy pasta the below
Click save
@namespace url(http://www.w3.org/1999/xhtml);
@-moz-document domain("forum.blockland.us") {
.signature img{
max-width: 0px;
}
}