How to uninstall few modules

I am new to Dolhin Community. I have install the application for our old boys school alumni service website without any problem. I have few questions like:

1. How to un-install few modules like Classifieds and Groups?

2. How to make Quick Search block populated with fields like "Name" (input box) or "Year" (drop-down box) rather then "sex" or "age".

3. I think Dolphin doesnt come with new templates because I didnt find any option to choose different templates. One i found is "Templates" under this page /admin/global_settings.php?cat=1&  but the drop-down menu shows only one template, ie, UNI. In the files, I noticed there are two template folders, base and tmpl_uni.  If I want to make the base as ACTIVE template, how to do that?   Secondly, are there any free templates available in boonex?

Please point me out in the right direction and I can work out on the rest.

Thanks.

any help ?

you can hide some modules into admin - Builders - navigation menu builder. 
There set every block you don't need to guest/members to off.

The standaard theme is uni , there are some themes to buy but also free. Look at www.expertzzz.com into download section.