To create the issue, they need to have the "permission" for "create issue", so check the permission scheme for that.
Then, look at the workflow. Specifically, look at the "close issue" transitions you want to stop them using. They have "conditions" on them that say things like "user must be in the role of developer" or "user must have the close issue permission". Make sure that your user does NOT match the conditions.
You may want to change the permissions and/or conditions to enable you to limit the user.
You must be a registered user to add a comment. If you've already registered, sign in. Otherwise, register and sign in.