The flex phrase was already off on the patch I was experimenting with (Citrus Tree). I was able to turn off the arp by:
Going to the EDIT Page/ARP Page
Setting the RESTART MODE to New Note
Setting the TEMPO SCALE to 4/4
I think it’s more just “tricking” the ARP and not so much turning it off, but I tried it on a few other TRIP patches and it seems to work.