Credit: Nero 3D (https://www.youtube.com/channel/UCmV40QWkVeRs_nAvEOE_P-g)
Handy G-Code to retract filament at end of the print enable you change nozzle after print end. G Code Basically retract filament after print is finished.
[gcode_macro PRINT_END] # Use PRINT_END for the slicer ending script - please customise for your slicer of choice gcode: M400 ; wait for buffer to clear G92 E0 ; zero the extruder G1 E-5 F3600 ; retract filament G91 ; relative positioning G0 Z1.00 X20.0 Y20.0 F20000 ; move nozzle to remove stringing TURN_OFF_HEATERS M107 ; turn off fan G1 Z2 F3000 ; move nozzle up 2mm G90 ; absolute positioning G0 X125 Y250 F3600 ; park nozzle at rear BED_MESH_CLEAR
Another Option (E3D)
Add (G Code to retract Filament)
G1 E-18 F800 ;retract filament from meltzone