Lemon Tree advice

Hi I would cut out all the dead stem an leave the new shoots to grow. Starloc is the best person to advise, so hopefully she will be around soon.
Good luck

Looking at the picture i would leave it , Because........

There is so little growing on the tree that any bit there is better than not there it may still be alive and providing circulation to the tree, there is some living , any growth is good its hard to tell on the older stems as they never look green

The shoots from the base of the tree are not lemon, they are the rootstock of the tree, leave them as well to give energy to the roots keeping the plant working, many would cut them off but its best to leave them to give energy and they may be the only bit alive, If the top dies totaly the branches from the base can be grafted onto , as they are they may even fruit..... they look something like seville orange or possibly grapefruit, i think seville orange though as most of the lemon trees i have seen over here are on seville orange even though its not usual anymore due to viruses in the past

I have had them like this before when the lights on the trees failed ,they usualy take a long time to start growing from the top, mine took till the end of august and then they were too tender to be outside in the winter that year