I run a mobile sawmill and sell firewood.
If the stem is clear of branches for, say, the first eighteen feet, and, say 50cms diameter at chest height, then it’s possibly worth milling, if not suffering from rot.
Unless it’s easy to strip and fell, you’ll need a good arborist team to put it on the floor. Minimum £600 per day. Milling £400 a day. Green ash sells for around £4 per cubic foot, so you’ll need a big tree to make it pay.
Don’t pollard an ash. It won’t thank you for it. Ash can be crown reduced well by a good arborist, but can also suffer once pruned.
There are plenty of trees near buildings causing no harm. Many trees are removed when they can be left well alone, often at the behest of insurers and ignorant surveyors.