To export all of your contacts, go to iCloud.com and sign in with your account credentials. Choose Select All from the drop-down menu to signify all of your contacts for export.
Open the Phone app or Contacts app on your iPhone. Tap Contacts at the bottom of the screen if you’re using the Phone app. To delete all of your contacts, deselect all of the accounts. All of your current contacts will be deleted.
Go to “Settings” > “Applications” > “Manage applications” > “All” > “Contacts” > “Storage” and choose “Clear data.” Note: Other data, such as your recent calls and favorites, will also be erased.
To delete a contact from iCloud.com, go to Contacts on iCloud.com and choose All Contacts in the sidebar. Then select one or more contacts you want to remove. Delete by clicking the Delete key then selecting Delete.
Hold down the Control key to select a number of contacts at once; then click the settings button on the lower left and pick delete.