Paste one of these scripts into your script editor with MEL selected. Then highlight the code snippet and press the play button to execute.
// Sets filter type to "Off" on ALL file textures
string $fileList[] = `ls -type "file"`;
for ($file in $fileList){
setAttr ($file + ".filterType") 0;
}
// Sets filter type to "Off" on selected file textures
string $fileList[] = `ls -sl -type "file"`;
for ($file in $fileList){
setAttr ($file + ".filterType") 0;
}