Really bad pruning!
Small Garden Design : Pruning
Quite obviously the privet above and this conifer got too large, but decapitation doesn’t work, it will still look like this next year and the next….many shrubs and conifers especially don’t regrow from old wood unfortunately.
So accepting mistakes happen, what to do, well the obvious choice is to remove it. It will be pretty hard to dig the roots out due to the pavement right next to it, but you can saw it off at ground level. The plant left, (I think it was a sorry looking heather) will gradually fill gap, if you don’t want to get rid of that as well, but I think in this scenario, it would be better to remove both.
Dig a new bed next to the stumps and plant that with something lovely. As the soil will likely contain the old roots you can’t get out, buy small replacement plants. That way they are easier to shoehorn in. Also go for plants that have shallow roots and that thrive in poorer soils – lavenders would be good, have a mix and match of colours, whites, lilacs and blues – much nicer than ‘headless Fred’ above.