> Could you tell me how to delete fields like SEVERITY , PLATFORM or OS
from
> the Bugs' creation page ?


copy template/en/default/bug/create/create.html.tmpl to
template/en/custom/bug/create/create.html.tmpl
Edit template/en/custom/bug/create/create.html.tmpl and change any
displayed text for OS/Platform/Severity to a hidden input:
value="[% default.bug_severity FILTER html %]">