Deductions & credits

There doesn't seem to be a way to delete any form or start over for just that section.  Have have so many hours inputting other information, starting completely over would be a huge nightmare.  There must be a way to alter one section right?  I'm not sure why it lets me alter any other information but the tuition is grayed out now that it's been entered.  

 

Is there a way to know if the system is correct in only allowing for 1/2 of the tuition paid to be used as a deduction?