You cannot hold down the button to bulk delete your Shaders at the Cryptarch. So I fiddled around a bit on LGS and managed to make it work. Unfortunatelly all I own are Logitech Products so I cannot test on anything else.
Step 1: Create a Multi-Key Macro
Step 2: Name it whatever you want, in my case, "Left Click"
Step 3: Right-Click the black box and choose "Insert Mouse Event > Left Button > Click"
Step 4: Rick-Click "Left Button Up" and choose "Insert Delay". This will automatically add a 0.5 second delay. Repeat this step twice.
Step 5: Under "Repeat Options" choose "While Pressed" and assign a millisecond delay of 1,000 (one thousand).
Step 6: Press "OK" to save it directly to the key or press "Add" to assign it manually.
This process takes one second per bulk deletion, but you may hold down the key for as long as you need.