Function delete_entry 

pub fn delete_entry<I, E>(
    delete_input: I,
) -> Result<HoloHash<Action>, WasmError>
where
    DeleteInput: TryFrom<I, Error = E>,
    WasmError: From<E>,

Delete an app entry. Also see delete.

This function accepts the ActionHash of the record to delete and optionally an argument to specify the ChainTopOrdering. Refer to DeleteInput for details.

#[hdk_entry_helper]
struct Foo(u32);

#[hdk_entry_defs]
pub enum EntryTypes {
   Foo(Foo)
}

let action_hash = create_entry(EntryTypes::Foo(Foo(50)))?;
let delete_entry_action_hash = delete_entry(action_hash.clone())?;

with a specific ChainTopOrdering:

delete_entry(DeleteInput::new(action_hash.clone(), ChainTopOrdering::Relaxed))?;