If the markings on the filament spool indicate that there is not enough material to complete your print, you can unload that roll
Unload the Current Filament [Change Filament]->[Unload Filament]->[Preheat PLA]
Wait until the filament unloading screen goes away
Release the filament from the extruder gear by squeezing you index finger and thumb in the locations pictured, while at the same time gentle pulling up on the filament
If the filament roll is empty, throw it away, if there is enough material for another print, wind the filament onto the roll and secure the end through the holes on the spool
Acquire a new role of filament, stored underneath the printers
Open the role and install it onto the spool holder being mindful that spool is in the correct direction (filament leaving the spool on top)
Bend the tip of the filament slightly to the left to make inserting it easier
Insert the filament into the Extruder, using your index finger and thumb to release the extruder gear, this may take a tries, but the filament should go about 3” into the extruder
Load the Filament [Change Filament]->[Load Filament]->[Preheat PLA]
Continue to [Purge More] until the old color is completely gone, ~3-7 times is typical
Remove any excess purged material from the nozzle by pulling on the cooled end of the strand opposite the nozzle DO NOT TOUCH the Nozzle
Press [Continue]