By default, deck stairs have a railing on both sides. You can choose to have a railing on the left side only or right side only, or remove them altogether.
To control the display of railings on deck stairs:
Click on the staircase to select it.
Right-click and select Properties, or select Edit > Modify Elements > Properties.
In the Railings area, uncheck the Include Railings check box if you don’t want any railings on your deck stairs. If you want one or more railings on the stairs, leave this check box enabled.
If you want a railing on the left side of the stairs, select Railing on left side from the drop box. If you want a railing on the right side of the stairs, select Railing on right side from the drop box. If you want a railing on both sides of the stairs, select Railing on both sides.
Click OK.