To simplify the given expression, we need to distribute the negative sign through the second polynomial and then combine like terms.
Step 1: Distributing the Negative Sign
We start with the expression:
\[
(2x^{3} - x + 5) - (6x^{3} + x^{2} - x + 1)
\]
Distributing the negative sign through the second polynomial gives us:
\[
2x^{3} - x + 5 - 6x^{3} - x^{2} + x - 1
\]
Step 2: Combining Like Terms
Next, we combine the like terms:
For \(x^{3}\): \(2x^{3} - 6x^{3} = -4x^{3}\)
For \(x^{2}\): There is only \(-x^{2}\)
For \(x\): \(-x + x = 0\)
For the constant terms: \(5 - 1 = 4\)
Putting it all together, we have:
\[
-4x^{3} - x^{2} + 4
\]
Final Answer
The simplified expression is:
\[
\boxed{-4x^{3} - x^{2} + 4}
\]