You can delete that by deleting history of browser. Browser history contains the sites that you have ever visited.
If you go to your history, you can click on the site you want to earse and hit the Delete button on your keyboard
click on tools. it should say delete browsing history in the list.
not unless they look under ALL your history, which is some where in the computor settings
Your parents may be able to check if they are the administators of the wifi, but otherwise just delete the browsing history
if your using internet explorer the in the SAFY tab on the top find "Delete browser History.
To find your last sites visited you go to your history tab and it will show you all the sites you have visited for the last week unless you are browsing in an incognito window.
recent web sites
displays a record of all the sites you have visited recently.
go to the favorites (where you see the star. usually in the left corner of screen) and right click the one you want to delete. it will give you a choice between expand, collapse, or delete. You click delete, obviously. If you want to find more things to do with your computer, go to Howiworkelectrics.com
I dont know what version of computer you have, but on mine you can go to your favorites (top left hand corner marked by star) and then a tab will say "history". From there you can choose what day and then delete the sites that you dont want shown.
Myspace and other sites like that.