Welcome to BLF! PS: You have to reduce that picture size. There's options in the image link to change the resolution. Use 800x600 or so, maybe little less.
Someone else might have experience in working with disabling modes, not sure (don't think so), but for me, I'd piggyback in a simplistic driver that supports the e-switch, and is configured for one mode only. A FET based driver would do it, but it would probably get you more power/amps than the stock driver, which might be a problem because your light is probably using fake LED's made by LatticeBright, and don't think they can handle high amps too well.
The problem is modes are implemented in firmware of the 8 pin MCU there, and is probably in the PIC family - most are. As far as I know, no one re-programs those. We've solved this problem many times over, but it calls for a driver replacement, or at least an MCU replacement custom wired. A driver like this: http://www.mtnelectronics.com/index.php?route=product/product&path=67_117&product_id=604, or a smaller one wired up piggyback style. Lot of options, nothing too cheap unless you can reflow boards, then buy a parts kit from MtnE to save a couple bucks.
A simple low budget (no cost), and very risky way is to directly wire up the batt+ to LED+, and batt- to LED-, but, the switch won't work (must unscrew the battery tube), and no other protections like low voltage detection. Might have to use thinner and longer wires to add resistance to reduce power to the LED's. This of course can be risky biz, if too much power, might blow out the LED's or melt the springs, etc...... Lots of fun in experimenting. 
I'm working on the driver/firmware for a similar group buy light (only 4 LED's) in the works here: https://budgetlightforum.com/t/-/39069, but obviously much more advanced than what you want.