Core properties can not currently be hidden and are required. Only optional custom properties can be hidden.
Its important to require there be data in the security question and answer fields because you could check the box at any time to require it for password recovery and if you do that and no data exists your users are not able to recover their passwords. So even though you are not using this feature now its best to require the data.
We don't have a customer ID property so that must be a custom property which you could remove form your mojoProfile.config (or maybe you are using a custom file as it can be specified from this Web.config setting:
<add key="mojoProfileConfigFileName" value="mojoProfile.config" />
Hope it helps,