An owner has the right to secure his/her lot, but there are some over-riding caveats.
1) You can’t breach fire regulations by securing external doors and windows, so certain door and window lock types that are sold through hardware stores may actually breach code;
2) Enclosing a patio, which is usually considered common property (albeit for exclusive use of the lot owner) is not an owners’ right. You would need your OC to have a special resolution passed to allow you to do this