Recipients of this message have either opened a Cash Account or have enabled Limited Option Trading permissions.  

Cash Accounts are not able to hold uncovered short call positions.  If you wish to upgrade to a margin account, please access Account Management under the Settings > Account Settings menu, you may choose the configure gear icon to update your Account Type.

You might also see that message even if you have a margin account but you have enabled the "Limited Option Trading" permissions. If you want to trade options but do not have enough experience, you can choose Limited Option Trading on the Trading Permission screen.

Limited option trading is available with any investment objective that you select on the Configure Financial Information screen. Limited option trading lets you trade these option strategies: Long Call or Put Covered Calls Short Naked Put: Only if covered by cash Call Spread: Only European-style cash-settledPut Spread: Only, European-style cash-settledLong Butterfly: Only European-style cash settledIron Condor: Only European-style cash settled.

To turn off Limited Option Trading log into Account Management or click on the menu bars icon in the upper left in the Client Portal then go to Settings > Account Settings > Trading Permissions and click on the configure gear icon > go to the section for Options and if US Options are selected look just to the right and uncheck the box for "Limited Option Trading" permissions then save your change.