Solid Hardwood, Engineered and Laminate Flooring - Laminate floors

We are going to attempt it ourselves. Half of Long room is Linoleum over an underlayment they must have used to make linoleum level with the carpet. Do we put underlayment down to match. A friend said that when we go to pull up the linoleum the underlayment there will get destroyed from Glue, that we should take it all down to the Wood subfloor and then install. I thought an underlayment would make surface area flat, better prepared.. Any thoughts??

If the floor is in fact flat to the laminate flooring manufacturers requirement then a vinyl or lino surface is fine. Either way, you must change 1/2 of the floor area and when your done the evevation or flatness must meet the requirements of the warrantee .