Remove rows in python less than a certain value

python doesn't use ! to negate. It uses not. See this answer
In this particular example != is a two character string that means not equal. It is not the negation of ==.

option 1
This should work unless you have NaN

result[result['Value'] > 10]

option 2
use the unary operator ~ to negate a boolean series

result[~(result['Value'] <= 10)]

Instead of this

df3 = result[result['Value'] ! <= 10]  

Use

df3 = result[~(result['Value'] <= 10)]  

It will work. OR simply use

df3 = result[result['Value'] > 10]  

I have another suggestion, which could help

df3 = result.drop(result[result['Value'] < 10].index, inplace = True)