Webster has been appointed interim head coach at Hull KR until the end of the Super League season, meaning City of Hull Academy Director Danny Wilson will now take over as Under 19s head coach for the interim period.
The coaching structure also includes former Hull FC player and coach Steve Crooks, as well as well-known local coach, Rob Wilson.
“We’ll be utilising our existing coaching staff in the interim period and review our position at the end of the season,” Wilson said.
“James has done a great job for us in recent months in helping instil the values the academy should work to and a strong technical infrastructure in which the academy can thrive.
“The availability and compensation cost of recruiting another high profile candidate at this stage of the season is untimely, whilst we’re also hesitant to unsettle a positive and ever-developing structure that is coming together at the academy.
“We have a very experienced coaching staff, particularly for working with and developing players at this level, that we believe are more than capable of continuing the excellent work we have started with this new venture.
“Jason and Rob are both developing well as coaches and have a great foil in Steve Crooks who has vast experience as a rugby league coach for many years, both at first-grade and junior development level.
The City of Hull Academy is made up of U19s and U16s and both recently started their new 2016 season.
A number of academy players have already enjoyed first-team experience with their respective club, with Ross Osborne, Reece Dean and Jez Litten all handed squad numbers at the Black and Whites this season, whilst the Robins awarded a first-team debut to Kieran Moran against Widnes on Friday and handed out a first team squad number to centre Joe Wardill last week.