how do i delete my 360 page but not my old profile?

Unfortunately, you cannot delete or get rid of a Yahoo! 360 account. It's linked to your primary Yahoo! ID. If you want to keep your Yahoo! ID for things like Mail, IM, Answers, etc. then you'll need to hide your 360.

There are a few different ways to do this,

1) Select the "Settings" option at the upper right of your 360 page and change all of you settings to 'Private'. This hides the majority of your content, if someone stumbles onto your page.

2) Perform option #1 and then select the first "Display Me As" option on the Settings page. Now your profile doesn't link to your 360 page. Also, UNcheck the "Activate Simple URL" setting and the "Friend Search" setting. This way people cannot guess your 360 page by sticking your yahoo id onto the end of 360.yahoo.com or searching for you by name or email address.

3) Perform options #1 and #2 and then delete your friends by selecting the "My Friends" link in the upper right of your 360 page. Select "Edit Settings" on a friend's name, then select "Remove <friend> from your Friends Page". Finally, delete all of your content, blogs, links to pictures, lists, reviews, etc. This pretty much makes your 360 inaccessible and/or unusable by anyone who happens to get there.