Yes, you have to de-solder the capacitors from the underside. Remove the main circuit board if possible to gain access to the underside.
Use a low-wattage (15W) soldering iron with a fine (thin) tip to minimise heat/melting damage to surrounding electronics and components.
As orx65 suggests, heat the solder from the underside, use a solder sucker (as orx65 showed) to remove any excess solder while still fluid, and pull the capacitor out from the other side.
^ Above pic shows the usual problematic capacitors on Virus B (shown within the dashed green box).
Thankfully the caps are not surface mounted.
I have further disassembly photos for a Virus Indigo, which is basically a Virus B with a keyboard and mod-wheels bolted onto it, which may show common detail regards the mainboard: Virus Surgery: Re-potting masterclass
.... I know it was being disassembled for a different purpose (repotting), though, so is just a rough guide as to what you may find.
The Virus is relatively modular to disassemble, there are three boards - the mainboard with all the circuitry (with all the jacks running along the top), a larger board which all the knobs attach to on the opposing side, and a third smaller board for the LCD. You only need the mainboard. You may need to remove a ribbon cable or two. Detach the boards from each other and you should have full unimpeded access to both sides of the mainboard. Be careful with the power on/off switch as, if it's like my Indigo, it may be attached to the metal casing and the wires are short and won't travel far.