class ActiveRecord::ConnectionAdapters::Table

See {connection.remove_index}[rdoc-ref:SchemaStatements#remove_index]

t.remove_index(:branch_id, name: :by_branch_party)
t.remove_index(name: :by_branch_party)
t.remove_index(column: [:branch_id, :party_id])
t.remove_index(:branch_id)

Removes the given index from the table.

def remove_index(column_name = nil, **options)
  raise_on_if_exist_options(options)
  @base.remove_index(name, column_name, **options)
end