Power Supply Discharge to De-energize a set of relays
In general it's desirable to allow the relays to switch as quickly as possible to maximize the life. If the (protection?) relays 3 and 4 are welding on due to slow turn off, you can use a more sophisticated circuit to switch them. I suggest a power supply supervisor chip driving a transistor (see below), which will snap on an off abruptly. 

Presumably relays 1 and 2 are being switched more frequently and are failing by wearing out. In that case, you should put a resistor or zener in series with the diode to allow the voltage to rise to a good portion of the rating of the drive transistors (taking care not to exceed the SOA). A zener across the transistor is another method. 

Keep in mind that any circuit has some inductance and you may not be able to achieve the ratings shown on the relay datasheet even if they are switched properly. You are also expected to break the wash seal on many relays to allow the 'stuff' to vent. 

A link to the relay specifications would be useful. If they are cruddy T90 style knock-offs, you may not be able to achieve the stated life even checking all the boxes off.