Jar files are listed in the SQLJ.JARS view. This information is documented in the Teradata Database "Data Dictionary" Reference.
DBC.JARS is a Data Dictionary view, and you are not permitted to delete rows directly from the underlying Data Dictionary table.
In order to remove a Jar file from your Teradata Database, you must call the built-in stored procedure SQLJ.REMOVE_JAR.
This is documented in the Teradata Database Reference book "SQL External Routine Programming", Chapter 8 "Administration", section "Removing Registered JAR or ZIP Files".