Remove deprecated stuff

| Q             | A
| ------------- | ---
| Bug fix?      | no
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | na
| Refs tickets  | na
| License       | MIT
| Doc PR        | na

Requires a `composer update` or `composer dump-autoload` after merge.