To Hide a Fixed Valued Array Parameter From the Size Selection Dialog Box (AutoCAD Mechanical Toolset)

If the Parameters Manager is not visible, click Content Editor tabManage panel Parameters Manager.
In the User Parameters section, in the row corresponding to the array parameter to hide, click in the Size Selection column.
Note:
All array parameters are listed in the User Parameters section.
Select Fixed.
In the Expression column, specify the value for the parameter.
The array parameter is no longer displayed in the Size selection dialog box when you insert the part/feature in the drawing area.