Postgres, two tables use the same sequence, how to delete one?
You were probably using a serial data type.

PostgreSQL documentation says this is equivalent to the following:

CREATE SEQUENCE tablename_colname_seq;
CREATE TABLE tablename (
    colname integer NOT NULL DEFAULT nextval('tablename_colname_seq')
);
ALTER SEQUENCE tablename_colname_seq OWNED BY tablename.colname;


Note the latest statement.

Based on https://www.postgresql.org/docs/current/sql-altersequence.html you will need to remove the "ownership" dependency:


  Specifying OWNED BY NONE removes any existing association, making the sequence “free-standing”.


Which in your case means:

ALTER SEQUENCE mytable_ident_seq OWNED BY NONE;


Or you may need to reassociate it with the proper table, using:

ALTER SEQUENCE mytable_ident_seq OWNED BY table_name.column_name;


After which you should be able to delete the table without consequences for the sequence.