Here is my html:
<p class="actions">
<input style="float: right" id="submit" type="submit" name="Create account" value="Update profile">
<button name="cancel" style="padding: 10px 10px" onclick="window.close(); return false">Cancel</button>
<button name="delete" style="padding: 10px 10px" onclick="window.location.href = 'https://88888.dev2.ext-dev.mysite.com/plugins/social/profile/delete?sessionKey=521f6a65e4b01c799ac48260&webSocketIdentifier=521f6a65e4b01c799ac4825f'; return false">Delete account</button>
</p>
I have used:
delete_account=@browser.element(:css => "p.actions > delete").click