@AuraEnabled(cacheable=true)
public static String  deleteContacts(List<String> contactIds) {
    List<Contact> returnList = new List<Contact> ();
    String query = ' SELECT Id,Name, LastName,Department,MobilePhone, Email FROM Contact WHERE id IN : contactIds ';
    for (Contact thisContact:  Database.Query(query)) {
         returnList.add(thisContact);
    }
    try {
      delete returnList;
      return'deleted successfully';
    }
    catch(Exception ex){
       return 'Problem occoured';
    }

}

JS Method
deleteSelected(){
    deleteContacts({
        contactIds :this.selectedIds
    })
    .then(result => {
        this.dispatchEvent(
            new ShowToastEvent({
                title: 'Success',
                message: result,
                variant: 'success',
            }),
        );
        return refreshApex(this.getContactList, { searchKeyWord: '$searchKeyWord' });
    })
    .catch(error => {
        this.error = error;
    });