Hi Bailu,
yes, you can delete the 'neXt' registration of an old computer on our server.
Please start the neXt on your old computer, press esc, change to license tab, press the key o and click onto deactivate license. Then you can activate the neXt on your new computer.
If you have already deleted the neXt there, simply download and start it. If necessary activate the neXt and then deactivate it. After that, it's deleted from our server.
All the best,
Klaus