#Python, 61 bytes (way too many)

lambda x:"".join(map(lambda y:(y.lower()!=x[0].lower())*y,x))

I imagine there is a better way to go about doing this, but I can't seem to find it. Any ideas on removing the "".join(...)?

Python, 61 bytes (way too many)

lambda x:"".join(map(lambda y:(y.lower()!=x[0].lower())*y,x))

I imagine there is a better way to go about doing this, but I can't seem to find it. Any ideas on removing the "".join(...)?

#Python, 61 bytes (way too many)

lambda x:"".join(map(lambda y:(y.lower()!=x[0].lower())*y,x))

I imagine there is a better way to go about doing this, but I can't seem to find it. Any ideas on removing the "".join(...)?

#Python, 61 bytes (way too many)

lambda x:"".join(map(lambda y:(y.lower()!=x[0].lower())*y,x))

I imagine there is a better way to go about doing this, but I can't seem to find it. Any ideas on removing the "".join(...)?

#Python, 63 bytes (way too many)

f=lambda x:"".join(map(lambda y:(y.lower()!=x[0].lower())*y,x))

I imagine there is a better way to go about doing this, but I can't seem to find it. Any ideas on removing the "".join(...)?

#Python, 61 bytes (way too many)

lambda x:"".join(map(lambda y:(y.lower()!=x[0].lower())*y,x))

I imagine there is a better way to go about doing this, but I can't seem to find it. Any ideas on removing the "".join(...)?