The "RENAME" command allows you to rename blocks, dimension styles, layers, line types, materials, table styles, text styles etc…
Rename command will be a better option in-order to rename the prefix and suffix of a layer name.
Layer names :
want to change “ABC” to “DEF”
Command : RENAME select Layers tab then type old prefix (ABC*) of your layers in Old name: field
Then type New prefix (DEF*) which you like to change in Rename to: field
click ok button, now all your layer prefix are changed to