Permissions such as these are managed through the Profile

Go to Settings (Top Right) > Profiles > Select the Profile name (or select the Edit option) > Select Edit Profile > you can select/deselect the options that you feel are appropriate for this profile.

In the example above I have removed the ability for users of that Profile to be able to Create, Edit or Merge any Helpdesk or Product records and they cannot delete any Helpdesk, Product or FAQ records, without restricting their ability to view any of these records.

If you want to limit the Import and Export features in OpenCRM, this is done in the bottom panel, selecting/deselecting in the same way.

For further information on apply Profiles to Users take a look at This FAQ