Why didn't Czar Nicholas II renounced his German titles during World War 1 like George V did?

George V renounced his German titles in July 1917. Nicholas II had abdicated in March 1917 and had been under effective house arrest as he was until his murder in 1918 do was in no position to renounce his German titles. If he had been allowed to live in exile in The UK it is likely he would have followed his cousin and renounced his German titles.

It was because George V of the United Kingdom was faced with anti german sentiment from the British public whilst bearing the german name of the dynastic house Saxe-Coburg and Gotha. The choosing of Windsor as the Dynastic name was a huge PR exercise to hide their german roots. At this time many aristocratic houses in Britain disguised their germen roots with Anglicised versions of their name the Battenberg's ( meaning Batten Mountain in german ) changed their name to the now famous Mountbatten ( Get it? Mount Batten ) Prince Phillip's maternal family name is one example

He probably didn't see the value in doing so.

Just wait for Empress Alexandra to answer.

He didn't care what people thought about him, it was part of the reason that he had to abdicate.

he was a colset kruat

Because he was dead.