Deductions & credits

One more question:

I am not allowed to choose OPT OUT option for this tax withholdings when it comes to the employment retirement plan, right? I tried to click OPT OUT, but I am not allowed.  I called the investment company, and that's what they explained. 

 

WITHHOLDING TAX WITHHELD % OF TAXABLE AMOUNT OPT OUT

Minimum Federal Withholding (20% required). Understand why?$500.00
 
 
Minimum MD State Withholding(7.75% required) Understand why?$193.75