you must be find and edit this (in your model tt file) :
<#
foreach (var navigationProperty in navigationProperties)
{
if (navigationProperty.ToEndMember.RelationshipMultiplicity == RelationshipMultiplicity.Many)
{
#>
[System.Diagnostics.CodeAnalysis.SuppressMessage("Microsoft.Usage", "CA2227:CollectionPropertiesShouldBeReadOnly")]
<#
}
#>
<#=codeStringGenerator.NavigationProperty(navigationProperty)#>
<#
}
}
#>
To this :
<#
foreach (var navigationProperty in navigationProperties)
{
if (navigationProperty.ToEndMember.RelationshipMultiplicity == RelationshipMultiplicity.Many)
{
#>
[System.Diagnostics.CodeAnalysis.SuppressMessage("Microsoft.Usage", "CA2227:CollectionPropertiesShouldBeReadOnly")]
[System.Xml.Serialization.XmlIgnore]
<#
}
#>
<#=codeStringGenerator.NavigationProperty(navigationProperty)#>
<#
}
}
#>