If you have directly created a PCB without a schematic then just delete the old package, add the new one and then add the old net names to the pins of the new package. * Note that we recommend that you always create a schematic fist, adding the correct BoM information (supplier, part numbers, etc.) and assigning the correct PCB package to each schematic symbol and then checking everything before you try to convert to PCB. If you have created and carefully checked a schematic you will have a smooth conversion to PCB with no package errors and if you then decide to change things, you can do this in the schematic and simply click `Update PCB...` in the Schematic Editor (or `Import Changes...` in the PCB editor) with no package and net errors. For more information please see (4), (5) and (6) in: https://easyeda.com/andyfierman/Welcome_to_EasyEDA-31e1288f882e49e582699b8eb7fe9b1f

Ok thanks !