Badly pruned apple tree

From looking at the photos it shows that the tree has been left to grow much too much. If it produces apples, and I don't see why not, then most of them will be out of reach. The idea is to keep the tree cut reasonably low so that you can pick them.

It needs some drastic pruning, apple trees are pretty tough, and it's difficult to explain how much to take off. Looking at your first picture I would be inclined to remove everything above a shallow arc drawn at a height that appears, from the angle of the photographer's view, to cut through the top of the top windows in the house behind. Not actually at the height of those windows but at the level of a line drawn on that photo.

As Graham B says, it will then produce lots of little shoots from the remaining length of the branches. Wait until they have grown six inches or so. Then you will need to thin those out and you start by removing a high proportion of those pointing in to the centre of the tree as they will only get in the way of each other.

In the old days they said you should always seal off the cuts on the thicker branches to prevent disease getting in (products you can buy to paint on the cuts) but nowadays, especially with apple trees, they say it is not the thing to do. I only do it on plum trees.

Sorry to disagree with you @Mike Allen but I stopped using Arbrex on apples twenty years ago and my almost 100 year old apple trees are no worse for it. I still use it for heavy pruning on summer pruned fruit trees.

This is a good time of year to prune apples.

 

I use the one that we have to clean the chimney

 

It's been pollarded in winter in the last 2-4 years and left to regrow. It needs a summer prune to thin a few branches and reduce the height/length of the remainder. Just FYI winter pruning results in strong regrowth and summer pruning is for shaping as a rule (stone fruit is different and should be done in summer).

The pruned branches will create fruiting spurs so more apples next year and there is no need to disinfect anything unless you're been using the tool for cutting diseased stuff prior.

From the look of it you might get away with an extendable pruner but a set of steps and a pruning saw might be best. If harvesting higher apples then get yourself an apple picker

 

There's never too much! We cook all ours and put them in the freezer - a few hundred pounds so far. I picked another 20lb this afternoon. Not many left now.