I have installed dokuwiki to my server.
It shows in mobile mode when I access to it with Android or iPhone.
But I want to show it as PC mode.
How can I?
Dokuwiki's API let determine if the client is mobile. Then it's up to the template to use this information or not.
You could try grep -rn ismobile . on your template code to see how it is used.
Ideally I would have added a comment to ask which template you use, but I'm afraid I don't have enough reputation to leave comments yet.