By using db<>fiddle, you agree to license everything you submit by Creative Commons CC0.
select v.name, left(name, patindex('% [(+]%', name + ' (') - 1)
from (values ('Mike Matthews +8012345678'), ('Matt Phillips (+8012345678)'), ('John Doe')
) v(name)
| name | (No column name) |
|---|---|
| Mike Matthews +8012345678 | Mike Matthews |
| Matt Phillips (+8012345678) | Matt Phillips |
| John Doe | John Doe |