Spring JPA #ManyToOne and #OneToMany delete - spring-boot

Question

I use Spring Boot backend for my application. I have 2 entities, Post and Comment. There are multiply comments for my posts. What I want:
If I delete my post, I want to delete my comments as well.
If I delete a comment, I want to delete only that one comment.
Here is my Post entity:
#Entity
public class Post{
...
#OneToMany(cascade = CascadeType.ALL, mappedBy = "post")
private Set<Comment> comments;
...
}
Here is my Comment entity:
#Entity
public class Comment{
...
#ManyToOne
#JoinColumn(name = "post_id", nullable = false)
private Post post;
...
}
This is how I tried to delete my comment:
#DeleteMapping("/{commentId}")
#RoleSecured({})
public ResponseEntity<Object> delete(#PathVariable Long commentId) {
commentRepository.deleteById(commentId);
return ResponseEntity.ok().build();
}
And this is how I tried to delete my post:
#DeleteMapping("/{postId}")
#RoleSecured({})
public ResponseEntity<Object> delete(#PathVariable Long postId) {
Post post = postRepository.findById(postId).orElseThrow(() -> new RuntimeException("Post not present in database"));
postRepository.delete(post);
}
This is my last try but I tried a lot of things, can you help me please how can I implement both deletes.
Delete of the post exception:
021-11-24 15:05:48.479 ERROR 23332 --- [nio-8080-exec-1] o.h.engine.jdbc.spi.SqlExceptionHelper : Cannot delete or update a parent row: a foreign key constraint fails (`buildtogether`.`comment`, CONSTRAINT `fk_comment_post_id` FOREIGN KEY (`post_id`) REFERENCES `post` (`id`))
2021-11-24 15:05:48.480 INFO 23332 --- [nio-8080-exec-1] o.h.e.j.b.internal.AbstractBatchImpl : HHH000010: On release of batch it still contained JDBC statements
2021-11-24 15:05:48.588 ERROR 23332 --- [nio-8080-exec-1] o.a.c.c.C.[.[.[/].[dispatcherServlet] : Servlet.service() for servlet [dispatcherServlet] in context with path [] threw exception [Request processing failed; nested exception is org.springframework.dao.DataIntegrityViolationException: could not execute statement; SQL [n/a]; constraint [null]; nested exception is org.hibernate.exception.ConstraintViolationException: could not execute statement] with root cause
java.sql.SQLIntegrityConstraintViolationException: Cannot delete or update a parent row: a foreign key constraint fails (`buildtogether`.`comment`, CONSTRAINT `fk_comment_post_id` FOREIGN KEY (`post_id`) REFERENCES `post` (`id`))
at com.mysql.cj.jdbc.exceptions.SQLError.createSQLException(SQLError.java:117) ~[mysql-connector-java-8.0.27.jar:8.0.27]
Delete of the comment exception: no exception, but not delete the comment.