Wolff–Kishner reduction converts a ketone (or aldehyde) into a hydrocarbon (alkane) by completely removing the carbonyl group ($\mathit{C}=\mathit{O}$).
It uses hydrazine ($\mathit{N}{\mathit{H}}_2\mathit{N}{\mathit{H}}_2$) and a strong base under high temperature.
Reimer–Tiemann reaction $\to$ Introduces a formyl group (–CHO) into phenols.
Aldol condensation $\to$ Forms β-hydroxy aldehydes/ketones.
Stephen reaction $\to$ Converts nitriles into aldehydes.
Therefore, the reaction used to convert a ketone into a hydrocarbon is Wolff–Kishner reduction.