Permission denied when deleting a unlinked file from php

When you try to remove a file, the following message appears:

  

( ! ) Warning: unlink(./files/ecommerce.vip): Permission denied in G:\apache\www\import_emails\index.php on line 28 Call Stack # Time Memory Function Location 1 0.0030 238584 {main}( ) ...\index.php:0 2 0.0078 240760 importa( ) ...\index.php:36 3 15.3884 1117344 unlink ( ) ...\index.php:28

Code PHP

unlink('./' . $pasta . $arquivo);