You can do this with gsub and using sapply to apply it per variable:
df <- data.frame( var1 = c("test","esten","blest"), var2 = c("testing","etsen","esttem"))df2 <- as.data.frame(sapply(df,gsub,pattern="t",replacement=""))df2 var1 var21 es esing2 esen esen3 bles esem