To delete a symbol definition, select Symbol Manager on the Symbols menu, choose a symbol, then click Import PNGs.
IMPORT PNG SYMBOLS enables you to select a folder of png or bmp raster images. These will be included in symbol definitions in the current drawing. When you've imported your symbols, you can make changes in the symbol manager and then save the drawing as a catalog.
Click on the image below for more information:
Choose Source Folder
Create Other Resolutions
The symbols names are the image file names, and the images are imported in alphabetical order.
File names should be limited to 28 characters.
Import PNG symbols can create varicolor symbols by stacking a varicolor image on top of a full color one. Make sure they are named the same, with the same resolution, with a filename suffix " vari_01" for the first, and "vari_02" for subsequent ones.