how to delete quartus2 has been bulit project files?

--- Quote Start ---

For your question, if you mean how to clean up the Quartus Project. You will have to manually delete files. The generated output files are the ones named .sof . If you on the other side perhaps just want to generate a new Quartus-File then try File/New. You then have to select the fileformat you want to use for the design. If you want to add a existing file go to the file-tab on your screenshot right click and add the file you have prepared.

(I recommend not to use blanks in Quartus-Project paths. What language do you speak normally? Try to rephrase your question with more details.)

--- Quote End ---

o ,i'm so sorry .i speak chinese.